Anisotropic Field Evaporation of Diatomic Species from Oxides and Nitrides

Published

May 21, 2012

Author(s)

Matthew D. Brubaker, David R. Diercks, R Kirchofer, Kristine A. Bertness, Norman A. Sanford, Brian Gorman

Abstract

Recent work using laser-assisted atom probe tomography on non-metallic materials has indicated that for many data collection conditions, anisotropic evaporation can occur. In some cases this can be attributed to a high laser energy leading to uneven heating of specimens, which may result in compositional determinations far from the known stoichiometry [1]. However, even in low laser energy conditions, where the correct stoichiometry is measured, uneven evaporation may still be observed in materials with significant bond ionicity as has been reported for GaN [2]. This may be a result of one or more of the following: surface anisotropy, differences in surface polarity, and modified surface states. These effects, as shown in Figure 1 for two specimens, may be particularly pronounced in hydrides, nitrides, oxides, and halides where the anions readily form strong diatomic bonds. This work is a first attempt to relate the observed phenomena to evaporation conditions, specimen orientation, and crystal planes. Initial results suggest that the crystal structure and orientation effects take precedence over evaporation conditions for a wide range of values.

Conference Dates

May 21-25, 2012

Conference Location

Tuscaloosa, AL

Conference Title

International Field Emission Society Conference

Pub Type

Conferences

Citation

Brubaker, M. , Diercks, D. , Kirchofer, R. , Bertness, K. , Sanford, N. and Gorman, B. (2012), Anisotropic Field Evaporation of Diatomic Species from Oxides and Nitrides, International Field Emission Society Conference, Tuscaloosa, AL (Accessed October 31, 2024)